1.The naturally occurring isotope rubidium-87 decays by beta emission to strontium-87. This decay is the basis of a method for determining the ages of rocks. A sample of rock contains 112.3 µg 87Rb and 6.5 mg 87Sr. What is the age of the rock? The half-life of rubidium-87 is 4.8 1010 y.
2.The half-life of calcium-47 is 4.536 days and it decays by the emission of a beta particle.
(a) Write a balanced equation for the decay of Ca-47. (Use the lowest possible coefficients.
(b) If 19.0 µg of Ca-47 is needed for an experiment, what mass of 47CaSO4 must be ordered if it takes 54 h for it to arrive from the supplier in ug ?
3.The radioactive isotope phosphorus-32 is often used in biochemical research. Its half-life is 14.28 days and it decays by beta emission.
(a) Write balanced equation for the decomposition of P-32. (Use the lowest possible coefficients
b) If the original sample were 224 mg of K332PO4, what amount of P-32 remains after 58.9 d in mg?
c). What percent of the sample has undergone decay?
4.Radon is a radioactive noble gas formed in soil containing radium. Radium-226 decays by emitting a single alpha particle to produce radon-222. Write the nuclear equation for this decay of radium-226. (Use the lowest possible coefficients. Omit states-of-matter in your answer.)